The present invention is generally directed to a method of bonding various materials such as foam materials to polymeric materials and to articles made therefrom. More particularly, the present invention is directed to a method of bonding foam materials to thermoplastic polymers using silane containing compounds.
Many useful articles are constructed by bonding foams to various structural materials. The foam can be incorporated into the product in order to provide thermal insulation, to provide insulation from noise, to act as a filler, to increase the structural integrity of the article, or for many other various reasons. In the past, when bonding foams to plastic materials, the foams have been primarily used with thermosetting polymers and with composite polymers such as fiberglass. Unfortunately, thermoset plastics are difficult to recycle once used.
In many foam and polymer applications, it would be very desirable to replace the non-recyclable plastics with recyclable materials, such as thermoplastic polymers. In the past, however, many difficulties have been encountered in sufficiently bonding the foam materials to the thermoplastic resins. The prior art teaches using cross-linking agents such as peroxides to form the bond. The cross-linking agents, however, render the polymers non-recyclable, thus removing one of the primary advantages of using them.
For instance, one prior art construction is directed to a process for the production of multi-layer moldings from a substrate member. The process includes bonding an elastomer foam to polypropylene containing a cross linking agent. The cross-linkable polypropylene and elastomer foam are combined and compression molded and then stored under hot conditions in order to increase the degree of cross-linking. As discussed above, however, cross-linking agents can render a thermoplastic resin thermoset in character making the polymer very difficult to recycle.
Generally speaking, the present invention is directed to a method for bonding various materials especially foam materials to thermoplastic polymers without using cross-linking agents. In particular, a silane compound is used for bonding a foam to the polymer. Unexpectedly, through the process of the present invention, no cross-linking agents, such as peroxides, are necessary for establishing a bond between the foam and the polymer. As shown in the accompanying figures, the method of the present invention can be used to construct watercrafts, pallets, thermocoolers, and many other useful articles.